PERFORATION GUN SYSTEM PRODUCING SELF-CLOSING PERFORATION HOLES

SYSTEME DE CANON DE PERFORATION PRODUISANT DES TROUS DE PERFORATION A OBTURATION AUTOMATIQUE

English Abstract

The invention relates to a perforation gun comprising an external gun barrel
(1) in the interior of which perforators (10) are located which can be ignited
via a fuse (11) extending through the gun barrel (1) and which, after
ignition, pierce the gun barrel (1) with perforation holes (13), whereby means
are provided which automatically close the perforation holes (13). According
to an embodiment of the invention, the means for automatically closing the
perforation holes comprise cartridges including a swellable two-component
foam. Said cartridges are located inside the gun barrel (1) and can be broken
up by the ignited fuse (11), thereby allowing foam to escape from the
cartridges, allowing it to swell and obliterate the perforation holes (13). If
the means for automatically closing the perforation holes (13) comprise a
sliding tube (4) that can be displaced after perforation by an adjusting
device by at least the diameter of the perforation hole (13), the sliding tube
(4) is located coaxially between the perforators (10) and the gun barrel (1).

French Abstract

L'invention concerne un canon de perforation comprenant un tuyau de canon extérieur (1) à l'intérieur duquel sont disposés des perforateurs (10) qui peuvent être allumés par un cordeau détonant (11) s'étendant dans le tuyau de canon (1) et qui, une fois l'allumage effectué, percent le tuyau de canon (1) par des trous de perforation (13), des moyens étant prévus pour obturer automatiquement ces trous de perforation (13). Dans un mode de réalisation de cette invention, lesdits moyens d'obturation automatique comprennent des cartouches contenant une mousse gonflable à deux composants. En outre, ces cartouches sont disposées dans le tuyau de canon (1) et peuvent être ouvertes par le cordeau détonant (11) allumé, ce qui permet à la mousse de sortir des cartouches, de gonfler et de boucher les trous de perforation (13). Lorsque les moyens d'obturation automatique des trous de perforation (13) comprennent un tuyau coulissant (4) qui peut être déplacé, après la perforation, au moyen d'un dispositif de déplacement, d'une distance correspondant au moins au diamètre du trou de perforation (13), ledit tuyau coulissant (4) est disposé de manière coaxiale entre les perforateurs (10) et le tuyau de canon (1).

Claims

7



WHAT IS CLAIMED IS:


1. A perforation gun having an outer gun barrel, arranged in an interior of
which
are perforators that can be ignited by a fuse leading through the gun barrel
and after
ignition pierce the gun barrel at penetration holes, wherein means for
automatic
closing the penetration holes are provided, and the means comprise a sliding
tube
displaced by an adjusting arrangement by at least the diameter of the
penetration
holes after being pierced, characterized in that the sliding tube is arranged
coaxially
between the perforators and the gun barrel.


2. A perforation gun according to claim 1, characterised in that the sliding
tube
is fixed in a starting position by a securing element that breaks up after
ignition of
the fuse and enables the displacement of the sliding tube.


3. A perforation gun according to claim 1, characterised in that the adjusting

arrangement is a tensioned spring.


4. A perforation gun according to claim 1, characterised in that the adjusting

arrangement is a pyrotechnic element ignited by the fuse.


5. A perforation gun according to claim 1, characterised in that the sliding
tube
is closed on an end facing a direction in which the sliding tube is to be
displaced
and is open on an opposite end, and as a result can be displaced like a
plunger by
pressure building up as a result of the ignition of the perforators.


6. A perforation gun according to claim 1, characterised in that the sliding
tube
has a wall thickness that permits radial expansion and fixation in the gun
barrel after
the sliding tube has been displaced as a result of pressure that has built up
in the
gun barrel after the ignition of the perforators.




8



7. A perforation gun according to claim 1, characterised in that a fluid is
disposed between the sliding tube and the gun barrel.

Description

CA 02539244 2011-04-26

1
PERFORATION GUN SYSTEM PRODUCING SELF-CLOSING
PERFORATION HOLES

The invention relates to a perforation gun.

A perforation guns are used in deep bore hole blasting in
the oil and natural-gas industries to tie the bore hole to
the storage horizon.

A perforation gun consists of an outer gun barrel,
arranged in the interior of which there are perforators -
usually hollow or projectile charges - that shoot radially
outwards through the gun barrel in the case of ignition.
Penetration holes remain in the gun barrel after the shot.
In order to ignite the perforators there is a fuse leading
through the gun barrel that causes the perforators to
ignite in the case of ignition.

In the case of this method a problem is presented by
residual pieces and fragments of the perforators and of
the components in the interior of the gun barrel that can
fall into the bore hole through the penetration holes
after the shot. In order to avoid this "debris"
(fragments of the perforators), in WO 00/49 271 it is
proposed that, in order to close the penetration holes
independently, a sliding tube, which can be displaced
outside the gun barrel on the outer wall of the gun
barrel, be displaced by means of an adjusting arrangement
by at least the diameter of the penetration hole after the
shot. This system has disadvantages in horizontal bore
holes, since here the sliding tube rests on the "casing
inner wall" and as a result displacement of the sliding
tube is rendered difficult. What is meant by the term
casing is the outermost tube that is introduced into the
bore hole and into which the perforation gun is inserted.


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The underlying object of the invention is to improve a perforation gun in such
a way
that with simple and reliable means emergence of fragments out of the gun
barrel
into the bore hole is avoided.

The gun has an outer gun barrel, arranged in an interior of which are
perforators
that can be ignited by a fuse leading through the gun barrel and after
ignition pierce
the gun barrel at penetration holes, wherein means for automatic closing the
penetration holes are provided, and the means comprise a sliding tube
displaced by
an adjusting arrangement by at least the diameter of the penetration holes
after
being pierced, characterized in that the sliding tube is arranged coaxially
between
the perforators and the gun barrel.

In accordance with the invention this object is achieved
in a first embodiment in that the means for the automatic
closure comprise cartridges with a swellable two-component
foam, and these cartridges are arranged in the gun barrel
and can be broken up by means of the ignited fuse, as a
result of which foam emerges out of the cartridges, swells
up and blocks the penetration holes.

In a preferred embodiment, a cartridge is arranged next to
each perforator.

In the case of perforation guns that have an outer gun barrel, arranged in the
interior
of which there are perforators that can be ignited by way of a fuse leading
through
the gun barrel and after ignition pierce the gun barrel at penetration holes,
with
means being provided for automatically closing the perforation holes, and
these
means comprising a sliding tube which can be displaced by means of an
adjusting
arrangement by at least the diameter of the penetration hole after being
pierced, it is
proposed that the sliding tube be arranged coaxially between the perforators
and
the gun barrel. As a result, emergence of fragments out of the gun barrel into
the
bore hole is avoided with simple and reliable means. In the case of horizontal
bore


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2a

holes, in which the outer wall rests on the casing inner wall, displacement of
the
sliding tube is possible in a reliable way.

In a preferred embodiment, the sliding tube is fixed in
its starting position by way of a securing element that


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breaks up after ignition of the fuse and enables the
displacement of the sliding tube.

The adjusting arrangement can be a tensioned spring or a
pyrotechnic element that can be ignited by means of the
fuse.

In a preferred embodiment the sliding tube is closed on
the side to which it is to be displaced and is open on the
other side, as a result of which the sliding tube is
formed like a plunger that can be displaced by means of
the pressure building up as a result of the ignition of
the perforators.

In order to fix the sliding tube after the displacement,
it is proposed that the sliding tube have a wall thickness
that permits radial expansion as a result of the pressure
that has built up in the gun barrel after the ignition of
the perforators.

Advantageously, arranged between the sliding tube and the
gun barrel there is a fluid. This fluid can be used to
control the timing of the radial expansion of the sliding
tube.

An embodiment of the invention is explained in greater
detail in the following with the aid of four figures.
Figure 1 shows a gun barrel 1 of a perforation gun for use
in the oil and natural-gas industries for tying a bore
hole to the storage horizon. The gun barrel 1 is closed
at its two ends by means of a respective connector or
seal 18. Arranged in the interior of the gun barrel 1
there is a sliding tube 4 and therein a charge carrier 9,
to which perforators 10 are secured. In the figures
shown, these perforators 10 are hollow charges. In order
to ignite these perforators 10, a fuse 11 is guided to the
respective ignition points of the perforators 10. The
fuse 11 is guided through the connectors or seals 18 into
the interior of the perforation gun.


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4

The inner tube or the sliding tube 4 is closed at one end,
for example by means of a cap 5. Lying next to the cap 5
there is a securing element 7, here a shearing pin, that
secures the sliding tube 4 before the shot in such a way
that the sliding tube 4 cannot be displaced in the gun
barrel 1 in the longitudinal direction.

Predetermined breaking points 3 can be introduced into the
gun barrel 1, opposite the perforators 10, so that after
the ignition of the perforators 10 the hollow-charge
stream 12 that forms (see Figure 2) can pierce the gun
barrel 1 in an unhindered manner.

Figure 2 shows a cutaway portion from the perforation gun
directly after the ignition. The fuse 11 has ignited the
perforators 10. The hollow-charge stream or hollow-charge
jet 12 that forms has pierced the sliding tube 4 and the
gun barrel 1. The metal housings of the perforators 10
are split up thereby and form splinter pieces and
fragments that form a portion of the "debris".

Figure 3 shows a cutaway portion from the perforation gun
directly after the shot. The hollow-charge stream 12 has
pierced the sliding tube 4 at the penetration hole 14 and
the gun barrel 1 at the penetration hole 13. A pressure
has built up in the interior of the sliding tube 4. This
pressure acts upon the sliding tube 4 in the direction of
the securing element 7, since the sliding tube 4 is closed
on the side of the securing element 5 by means of a cap 5
and is open on the opposite side. "Debris" 17 has formed
in the interior.

Figure 4 shows a cutaway portion from the perforation gun
after the shot. As a result of the pressure in the
sliding tube 4, the securing element 7 has been sheared
off, as a result of which the sliding tube 4 has been
displaced as far as the adjacent connector or seal 18. As
a result, the remaining small portions or the debris 17
cannot leave the gun barrel 1. What is not shown is that


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the inner tube 4 has become inflated after the shot and
has thus become wedged with the gun barrel 1.

The invention thus consists of a mechanism that closes the
perforation holes or penetration holes 13 in the gun
5 wall 2 after the shot and thus prevents the "debris" 17
from emerging. Foam cartridges or, as described, a slide
or rotary mechanism can be used as a closure mechanism.
In the case of the foam cartridges, some perforators 10
are replaced by cartridges with a two-component foam. By
means of the fuse 11 that ignites the perforators or
charges 10, the cartridge is caused to react, and the foam
swells up and blocks the penetration holes 13.

When a sliding or rotary mechanism is used, a second tube,
a sliding tube 4, which is displaced by at least the
diameter of the penetration hole 13 after the penetration
(either longitudinally: sliding mechanism, or
transversely: rotary mechanism), is inserted into the gun.
In Figure 1, the path of displacement is marked by an X
(see reference numeral 8). A pre-tensioned spring can be
used for the movement of the inner tube or second tube or
sliding tube 4 after the shot. The sliding tube 4 is
fixed in the starting position by way of a securing
element 7 which is destroyed by the fuse 11, for example.
Pins, snap rings or screws, for example, can be used as
the securing element 7. The destruction can also be
effected, for example, by way of a pyrotechnic element -
possibly even with a delay-action composition. The
internal pressure in the gun after the shot, caused by the
reaction products of the explosives in the perforators 10,
can also be used to move the slide mechanism or the slide
tube 5 (sic). If the slide tube 4 is closed on the side
to which it is to be moved and is kept open on the other
side, this sliding tube 4 can be moved like a plunger.
The internal pressure can only be relieved through the
perforation holes 14 and the leadthroughs 6 for the
fuse 11. The time until the pressure has been completely


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reduced is sufficient to displace the sliding tube 4 and
thus to close the penetration holes 13, 14. At the same
time, the gas pressure causes the sliding tube 4 to
inflate (also known for conventional perforation guns by
the term "gun swell"). The expanding sliding tube 4 can
become wedged with the inner wall of the outer tube or gun
barrel 1 and thus cannot slip back. The time of this
expansion can be controlled, for example, by way of a
fluid between the inner and outer wall. Grease or
silicone oil, for example, can be used for this purpose.

Representative Drawing